In order to form patterns in the manufacture of semiconductor devices and the like, microfabrication of organic or inorganic substrates is performed using a pattern-transfer method in which a lithography technology, a resist development process, and an etching technique are applied.
However, along with the progress of high integration of semiconductor devices in circuit boards, it has become difficult to correctly transfer an optical mask pattern to a resist film in an exposure step. For example, during a microfabrication process of a substrate, a dimensional error (deviation) may be produced in the pattern formed due to the effect of a standing wave of light formed in a resist film. In order to reduce the effect of such a standing wave, an antireflection film is formed between the resist film and the substrate surface.
A resist pattern is also used as a mask when a substrate with a silicon oxide film, an inorganic interlayer dielectric, or the like formed thereon is processed. It is necessary to reduce the thickness of the resist film and the antireflection film along with the progress of miniaturization of patterns. Since slimming of a resist film lowers mask performance of the resist film, there is a tendency that it is more difficult to provide a substrate with desired microfabrication without damaging it.
As a solution to this problem, a method of forming an underlayer for processing on an oxide film or an interlayer dielectric of a substrate to be fabricated, transferring a resist pattern to the underlayer, and dry-etching the oxide film or the interlayer dielectric using this underlayer film for processing as a mask is used. Since the reflectance of such an underlayer for processing changes with the film thicknesses, it is necessary to adjust the composition and the like to minimize the reflectance according to the film thickness. Other requirements demanded of the underlayer for processing include capability of forming a resist pattern without a skirt-like foot and the like, excellent adhesion to the resist, a sufficient masking property when processing an oxide film and an interlayer dielectric, excellent storage stability as a solution, and the like.
However, the underlayer for processing a substrate proposed heretofore, for example, an underlayer for processing made from a composition containing a hydrolyzate and/or a condensate of a specific silane compound (refer to patent documents 1 and 2) did not satisfy all of these requirements. The materials have the problems of poor adhesion to resist patterns and the like.
[Patent document 1] Japanese Patent Application Laid-open No. 2000-356854
[Patent document 2] Japanese Patent Application Laid-open No. 3-45510